The Digestive System By: Kendall and Joel

1. The Digestive System By: Kendall and Joel • Overview • The digestive system is made up of many organs from the mouth to the anus called the digestive tract. It helps our body to break down food and absorb nutrients that our body requires. • Mouth • Digestion starts here • Teeth chew food to break it down and saliva also helps break down food to make it easy to swallow • The chewed up food is called ‘bolus’ • Esophagus • Moves food from the throat to the stomach using muscular contractions • The epiglottis, which is a small flap at the opening of the trachea, makes sure no food enters the windpipe • Located in between the heart and the spine • Stomach • Stretchy sack shaped like the letter ‘J’ • Has three jobs: • Store food you’ve eaten • Break down food to what is now called ‘chyme’ • Slowly empty broken down food into intestine • Gastric acids aid in the breaking down of food and killing harmful bacteria • Small Intestine • 6.7m long • Breaks down food even more • Aids in the absorption of nutrients i.e. Vitamins, proteins, carbsand fats by diffusion and then transports to capilleries • Made up of three sections: • Duodenum • Jejunum • Ileum • Pancreas • Pancreatic juices (pancreatic juice alkaline) stabilizes pH in duodenum which provides a good environment for enzymes • Pancreatic juice is made by cell clusters called acini • Remaining cells stay in pancreas and produce insulin, glucagon, somatostatin, and pancreatic polypeptide • Two ducts within the pancreas release these cells one going through the liver and gall bladder and one directly to the small intestine

2. Liver • Filters out harmful substances and wastes • Decides how many nutrients should go to the body and how many should stay in storage • Produces bile to give to the duodenum to aid in the breaking down of fat globules • Also aids to regulate the pH in duodenum • Regulates blood glucose • Proteins and amino acids are synthesized • Large Intestine • 1.5m • Cecum takes food from ileum and passes it to the colon • Made up of: • Ascending colon • Transverse colon • Descending colon • Sigmoid colon • Main functions include • Peristalsis, which mixes chyme and sends in through the intestine • Bacterial digestion in which bacteria digest waste products and release gasses • Absorption in which nutrients are absorbed • Defecation which is the movement of feces • Appendix • Serves immunity functions and made up of lymphoid tissues • Rectum • Last 20 cm of the intestine • Anal Canal • Controls movement of feces in the last 3cm of the intestine How long are the small and large intestines when combined? How many litres of saliva does the average adult produce per day? Name the three sections of the small intestine. Name the three jobs of the stomach.